A gas turbine engine, also referred to as a combustion turbine engine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in between.
The basic operation of a gas turbine is that fresh atmospheric air flows through the compressor, which brings the air to higher pressure. Energy is then added by spraying fuel into the air and igniting it so the combustion generates a high-temperature flow. This high-temperature high-pressure gas enters a turbine, where it expands down to the exhaust pressure, producing a shaft work output in the process. The turbine shaft work is used to drive the compressor and other devices such as an electric generator that may be coupled to the shaft. Gas turbines may be used to power aircraft, trains, ships, electrical generators, or even tanks.
When a gas turbine is operated in a dusty environment, the intake air can include solid particulate matter, such as sand and dust, suspended in the intake air. If these particles are ingested into the gas turbine, they can cause significant harm to the engine.
Helicopters that operate in dusty and sandy environments are a special concern for intake of particulate matter. The downwash caused by the rotor blades during landing and takeoff lifts particles from the ground into the air. As a result, clouds of dust form around the helicopter. These dust clouds can be thick enough to block visibility—this condition is termed “brown out.” A helicopter engine operating unprotected from dust and sand in these types of environments can be expected to have a small fraction of the life expectancy of a typical helicopter engine.